Illumination of the work area within the mouth has received a great deal of attention due to the importance of the problem, and a great variety of devices have been employed for this purpose, such devices including a reflector on the forehead of the dentist, overhead lights with special reflectors and special diffusors, and, more recently, fiber-optic bundles and light-conductors in the form of shaped plastic or glass rods. The fiber-optic bundle has received particular attention due to the fact that it can provide illumination which is concentrated at the head of the handpiece.
A preferred light-source for use in connection with fiber-optic bundles has been the projection-type halogen bulb inside a case which is cooled by an electric fan. The light emitted by this bulb is directed to one end of the flexible fiber bundle which runs the length of the dental air supply hose, the bundle being disposed either inside or outside the hose.
The preferred source of light pursuant to the present invention is a quartz-halogen bulb having a lens in the tip thereof to focus the light from a bulb on the end of the light conductor. For proper operation, the temperature of the light bulb must be high, a condition which results in the emission of considerable radiant heat. The quantity of heat emitted can be sufficiently great so that the enclosure could become unbearably hot to the hand of the operator if cooling means were not provided. Hutchinson U.S. Pat. No. 3,634,935 teaches the use of an incandescent lamp specifically excluding the use of a quartz-halogen lamp and copes with a lesser heat removal problem by passing water through a tubular coil in a chamber surrounding the light source. The use of a quartz-halogen lamp pursuant to the present invention requires a careful balance for effective cooling. If the cooling is too effective, the bulb will not operate at high efficiently, and if the cooling is inadequate, the enclosure can become uncomfortably hot. Another problem is that the quartz-halogen bulb may fail in use, in which case the dental procedure must be interrupted for replacement of the bulb. Where the bulb must be removed from a housing or from within a water-jacket as is the case with the Hutchinson device, the removal of the bulb can be a time-consuming as well as a delicate operation requiring skillful manipulation.
In our earlier application, we disclosed a construction which successfully copes with the problem of maintaining the bulb at high temperature while cooling the housing of the illuminator. However, it would be desirable to make it easier to replace the bulb rapidly and easily in the event of failure thereof. The present invention is designed to solve the problem of easy replacement of the bulb while maintaining the balance between cooling of the housing and the necessary high temperature of the bulb.